A better Spark Out circuit. - Page 3 - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


MEGAsquirt A place to collectively sort out this megasquirt gizmo

Reply
 
 
 
LinkBack Thread Tools
Old 07-01-2009, 09:55 PM   #41
Boost Pope
Thread Starter
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Delicious and Moist.
Posts: 26,323
Total Cats: 1,920
Default

Quote:
Originally Posted by AbeFM View Post
You might have to dig around the layout a bit, but that should give you the inversion you were looking for, without adding parts?
We don't merely need inversion, we need the circuit to be off when the CPU is off.

When the CPU is inactive, its output pins are hi-z. A PNP won't conduct unless it's got negative base current, and that won't happen with the CPU tri-stated.



Quote:
Originally Posted by JustinHoMi View Post
It would be nice to have a simpler way of doing this for new builds!
It'd be nice if Grace Park had been waiting in my hotel room when I got back from dinner.

Didn't happen.
Joe Perez is offline   Reply With Quote
Old 07-02-2009, 04:25 AM   #42
Elite Member
iTrader: (3)
 
AbeFM's Avatar
 
Join Date: Aug 2006
Location: San Diego, CA
Posts: 3,048
Total Cats: 8
Default

So why can't you use a PNP instead of the NPN that drives the diode?

Oh, and sorry, if I'd known you were into her, I wouldn't have gone there. I'm sure she's looking for a shoulder to cry on since I haven't returned her calls....
AbeFM is offline   Reply With Quote
Old 07-02-2009, 05:13 AM   #43
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,366
Total Cats: 1,327
Default

******* hell. My 460s would give the pop on start up once every 2 weeks, but the RC750s are doing it every time the car sits overnight. I need to do this now. -.-
Savington is offline   Reply With Quote
Old 07-02-2009, 09:31 AM   #44
Boost Pope
Thread Starter
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Delicious and Moist.
Posts: 26,323
Total Cats: 1,920
Default

Quote:
Originally Posted by AbeFM View Post
So why can't you use a PNP instead of the NPN that drives the diode?
Show me a schematic of what you have in mind. I may just be mis-understanding what you're saying.
Joe Perez is offline   Reply With Quote
Old 07-03-2009, 12:03 AM   #45
Junior Member
iTrader: (4)
 
Join Date: May 2009
Location: Athens GA
Posts: 434
Total Cats: 3
Default

In regard to using a PNP instead of the NPN transistor in the original circuit. Can't we connect the output of the CPU to the base of a PNP with its collector connected to ground and the emitter connected to the -ve side of the LED. Then if we bias the base to the ground with a resistor we should be able to drive the transistor to conduct when the output from the CPU is low/floating. The output to the ignitior should then follow the output from the CPU.

I couldn't find a tool to draw circuits on my mac, hence the wordy description of the circuit.

Disclaimer: I am not an electronics expert so pardon me if this is wrong or stupid.
redrider706 is offline   Reply With Quote
Old 07-03-2009, 01:22 AM   #46
Boost Pope
Thread Starter
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Delicious and Moist.
Posts: 26,323
Total Cats: 1,920
Default

Quote:
Originally Posted by redrider706 View Post
I couldn't find a tool to draw circuits on my mac,
My name's Joe, and I'm a PC. We've got an app for that.

Seriously, I think this is what you & Abe are describing:



The reason I've had concerns here is that you need a small enough resistance to reliably turn on the transistor when the CPU is in la-la land, yet as the value of R goes down, the current which the MS is pissing away out of PTC0 / PTC2 to ground (when on) goes up. I've just been too damn lazy to look up the minimum IB needed to drive the ZTX553, which I'd assumed to be quite high, given its max IC of 1A (and the fact that PNPs usually suck in this regard). Having done so just now, I see that it is in the μA range.

Might work. Try it and find out. Take your pick- desolder a pair of transistors, clean out the holes, and replace them with two other transistors and a couple of tacked-on resistors, or add two additional transistors and resistors in the proto area.
Joe Perez is offline   Reply With Quote
Old 07-03-2009, 02:29 AM   #47
Junior Member
iTrader: (4)
 
Join Date: May 2009
Location: Athens GA
Posts: 434
Total Cats: 3
Default

Quote:
Originally Posted by Joe Perez View Post
My name's Joe, and I'm a PC. We've got an app for that.
What program do you use PC?

Quote:
That's the circuit I am talking about.
Can you calculate the resistor values please?

I am still building my MS2 for my 91.
I am in the process of trying to figure out all the different mods I want and how to assemble them.
I will try the PNP circuit while I assemble the spark output circuit.

Thanks.
redrider706 is offline   Reply With Quote
Old 07-03-2009, 02:33 AM   #48
Junior Member
 
Join Date: Jul 2005
Location: Hillsborough, NC
Posts: 273
Total Cats: 0
Default

Eagle CAD will run on Mac, Linux, and Winblows:

CadSoft Online: Download
JustinHoMi is offline   Reply With Quote
Old 07-03-2009, 04:32 AM   #49
Elite Member
 
Join Date: Jul 2005
Posts: 6,454
Total Cats: 80
Default

If the CPU output is 0-5V, then 470 ohms for the upper right hand (pullup) resistor is plenty, and 4.7k-10k for the base to ground resistor will be fine. The leftmost horizontal resistor is unnecessary.

Just about any TO-92 PNP will work, such as the 2N2905 or the 2N5551.
JasonC SBB is offline   Reply With Quote
Old 07-03-2009, 09:46 AM   #50
Boost Pope
Thread Starter
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Delicious and Moist.
Posts: 26,323
Total Cats: 1,920
Default

Quote:
Originally Posted by redrider706 View Post
What program do you use PC?
I use the free schematic editor that comes with the ExpressPCB package, for which Abe criticizes me on the grounds that Eagle is better.

Quote:
Originally Posted by JasonC SBB View Post
If the CPU output is 0-5V, then 470 ohms for the upper right hand (pullup) resistor is plenty, and 4.7k-10k for the base to ground resistor will be fine. The leftmost horizontal resistor is unnecessary.
The leftmost horizontal resistor is part of the standard 3.0 layout. It's R26 / R29 on page 7 (R3.0).

Bear in mind that the lower the better for the +5 pullup, since it dictates the current available to drive the igniters which as we've shown from past experience, are hugely capacitive. 220/330 is preferred here, as little as 100 is really ideal when you're dealing with a 2222 or similar.
Joe Perez is offline   Reply With Quote
Old 07-03-2009, 02:49 PM   #51
Elite Member
 
Join Date: Jul 2005
Posts: 6,454
Total Cats: 80
Default

The Toyota and Nissan COPs I tested didn't have capacitive loady inputs. I've posted how much current they require in the big COP thread.
JasonC SBB is offline   Reply With Quote
Old 07-03-2009, 08:21 PM   #52
Boost Pope
Thread Starter
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Delicious and Moist.
Posts: 26,323
Total Cats: 1,920
Default

Quote:
Originally Posted by JasonC SBB View Post
The Toyota and Nissan COPs I tested didn't have capacitive loady inputs.
I didn't create this mod only for people with COPs.

In my personal opinion, the NPN design is more robust, and not significantly more complex.

Last edited by Joe Perez; 07-04-2009 at 02:50 AM. Reason: Schpelling (hey, I wrote this on an airplane while drinking scotch. Cut me some slack.)
Joe Perez is offline   Reply With Quote
Old 07-03-2009, 08:22 PM   #53
Elite Member
iTrader: (3)
 
AbeFM's Avatar
 
Join Date: Aug 2006
Location: San Diego, CA
Posts: 3,048
Total Cats: 8
Default

Quote:
Originally Posted by Joe Perez View Post
Seriously, I think this is what you & Abe are describing:


Without thinking it out, basically, yeah - stuffing the different part in the same hole. Of course, a small, surface mount resistor would comfortably attach to the bottom of the board to pick up both pins, so no wires to run.

Quote:
The reason I've had concerns here is that you need a small enough resistance to reliably turn on the transistor when the CPU is in la-la land, yet as the value of R goes down...
(blah blah a bunch of technical crap someone who actually knows what they're talking about would probably say)

Might work. Try it and find out. Take your pick- desolder a pair of transistors, clean out the holes, and replace them with two other transistors and a couple of tacked-on resistors, or add two additional transistors and resistors in the proto area.
Well, the idea is for fresh builds, if it's put this part in instead of another, ok. You're right, tearing apart an existing board is more work and slightly risky (lifted pads, etc)


Quote:
Originally Posted by Joe Perez View Post
I use the free schematic editor that comes with the ExpressPCB package, for which Abe criticizes me on the grounds that Eagle is better.
Actually, I've been using KiCAD - reminds me a lot of orcad. Eagle has really annoying limitations. And it's cross platform, so you can share with weird open-source/linux people. Maybe it works on mac? I dunno. Anyway - one package all the way through fab, why not?


Seriously, it's all about COPS, they are such a joy to work with. Everyone should buy them next time they need cables, costs about the same and you're set for life.
AbeFM is offline   Reply With Quote
Old 07-04-2009, 02:52 AM   #54
Boost Pope
Thread Starter
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Delicious and Moist.
Posts: 26,323
Total Cats: 1,920
Default

Quote:
Originally Posted by AbeFM View Post
Well, the idea is for fresh builds, if it's put this part in instead of another, ok.
This, from the man who failed to implement this freely available design on his NB PnP board (and who still hasn't paid me any ******* royalties on the A/C circuit that he stole)
Joe Perez is offline   Reply With Quote
Old 07-05-2009, 01:56 PM   #55
Elite Member
iTrader: (3)
 
AbeFM's Avatar
 
Join Date: Aug 2006
Location: San Diego, CA
Posts: 3,048
Total Cats: 8
Default

I never have issues with 'premature ignition' in my car. Maybe you should speak with a doctor about it?
AbeFM is offline   Reply With Quote
Old 07-15-2009, 10:23 AM   #56
Elite AbsurdFlow Member
 
Laur3ns's Avatar
 
Join Date: Mar 2008
Location: Enschede, NL
Posts: 2,058
Total Cats: 11
Default

Since my car is not driving anyway, I've decided to go ahead and order the parts I need for this mod.

2x 2N2222 TO18

Data sheet:
http://www2.produktinfo.conrad.com/d...219_2N2222.pdf
Laur3ns is offline   Reply With Quote
Old 07-15-2009, 10:40 AM   #57
Elite AbsurdFlow Member
 
Laur3ns's Avatar
 
Join Date: Mar 2008
Location: Enschede, NL
Posts: 2,058
Total Cats: 11
Default

I've expaneded the write up from Matt. This is correct right?

Quote:
We are aware of that circuit, but we haven't tested it for ourselves.
However, if you want to try putting it on an MSPNP, here's what you
would do.

1. Desolder the jumpers from PAD1 and PAD3.

2. Take a PN2222(A) transistor and connect it as follows:
* Emitter pin to ground (PAD4)
* Base pin to PAD1
* Collector pin to the jumper that previously connected to PAD1

3. Take a second PN2222(A) and
* Take a PN2222(A) transistor and connect it as follows:
* Emitter pin to ground (PAD4)
* Base pin to PAD3
* Collector pin to the jumper that previously connected to PAD3

4. Disconnect the coils and power up the MSPNP.

5. In MegaTune, change the Spark Output Inverted setting to YES and burn
to ECU.

6. You can now connect the coils.

The pull up resistor Joe mentions is already on
the MSPNP adapter card and stays in place.
Attached Thumbnails
A better Spark Out circuit.-npn.png  
Laur3ns is offline   Reply With Quote
Old 07-15-2009, 11:08 AM   #58
Supporting Vendor
 
Matt Cramer's Avatar
 
Join Date: Sep 2006
Posts: 2,266
Total Cats: 51
Default

Looks good...
Matt Cramer is offline   Reply With Quote
Old 07-15-2009, 12:05 PM   #59
Elite Member
 
Join Date: Jul 2005
Posts: 6,454
Total Cats: 80
Default

Oh? Whose igniters have super capacitive inputs? Miatas?
JasonC SBB is offline   Reply With Quote
Old 07-15-2009, 12:59 PM   #60
Elite AbsurdFlow Member
 
Laur3ns's Avatar
 
Join Date: Mar 2008
Location: Enschede, NL
Posts: 2,058
Total Cats: 11
Default

Quote:
Originally Posted by JasonC SBB View Post
Oh? Whose igniters have super capacitive inputs? Miatas?
Explain please?
Quote:
Desolder the jumpers from PAD1 and PAD3.
Does this mean remove the two red wires below the surface of the board? Ex. PAD1 and IACB2B en PAD3 and X ?
Laur3ns is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
FS/FT: 03.5 Mazdaspeed Protege leatherface24 Cars for sale/trade 15 10-16-2015 12:35 PM
Time to start learning and play with tuning The Gleas MEGAsquirt 3 10-01-2015 10:30 AM
01-05 Fab9 PNP COPs (used) FrankB Miata parts for sale/trade 6 09-30-2015 12:48 PM
In need of AEM guidance W/pics E=MC^2 AEM 1 09-17-2015 01:34 PM
Obligatory "N00B" post! D_Breezy Meet and Greet 5 09-08-2015 06:37 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 08:29 AM.